solving a matrix equation modulo m

I'm given a matrix 'A' and a vector 'b' and a positiv interger 'm' (m does not have to be prime). 'A' is a matrix with more rows than collums, so it is not quadratic. I would like to find the solution 'x' of the equation: A*x = b (mod m).

I have tried to manage it with e.g.:

A.solve_right(Integers(m),p),

but this works only if m is prime. I also was able to solve my problem if I explicitly insert the equations like this:

gp('matsolvemod([1,2;1,3],6,[1,0]~,1)')

But I need something, where I just have to specify 'A' and 'b' (and of course m). Can somebody help me?

Comments

Hello and thanks for the answer. If I try your example above I get the following error:
TypeError: base ring must be an integral domain
I get this error if and only if m is not prime (in this case m=15 is not prime). I tried your example with the free sage provided online at [sagemath](http://www.sagemath.org/) and there it works fine. So could it be, that my version is not up to date, although I downloaded it last week?